1. Field
An embodiment of the invention is directed to a composition and method for reducing exotherm in actinic curing of urethane (meth)acrylate oligomers on fingernails. Other embodiments are also described and claimed.
2. Background
Urethane meth(acrylate) oligomer based nail formulations are used in the nail care industry to form durable coatings on fingernails. Such formulations also include monomers which form polymer chains within the formulation upon curing. The formation of polymer chains, however, is an exothermic reaction which generates heat. The heat that is generated has to be dissipated quickly, so that the client does not face any discomfort. Adding additives like pigments and glitters sometimes increases the polymerization rate tremendously such that the system does not have time to dissipate the heat quickly, causing the client extreme discomfort due to heat.
One way to mitigate this undesired phenomenon is to adjust the amount of photoinitiator(s) (PI) in the starting base. It would, however, be extremely difficult from an inventory standpoint to maintain so many different bases. In addition, since additives (e.g., pigments and glitters) vary from batch to batch, PI(s) would still have to be adjusted in the base designated for that particular SKU. Though feasible, this would be less than an ideal solution to the problem.
Another possible solution is to keep the same base formation but change the intensity of irradiated light. This is not a practical solution for lamps that will be used in salons. Even if lamps exhibiting different intensities were feasible, the manicurist has to know beforehand the level of intensity that a particular batch of gel needs to cure to form a coat on a fingernail without creating a heat spike. The package would therefore have to carry information regarding the intensity to be used for that particular batch, another hurdle to making a successful brand.